Abstract: Our previous work presented the construction of transgenic microalgae Anabaena sp. PCC7120 (A. 7120) with human tumor necrosis factor-α (hTNF-α) gene. We currently described the preliminary studies on optimal growth conditions for transgenic A. 7120 in the laboratory scale. The data we provided here showed that the optimal growth temperature and pH are at 2530℃, and pH 7.07.5, respectively; the net photosynthetic oxygen elution rates of the transgenic A. 7120 under different photon flux densities measured here suggested that both the saturated and compensated light densities of the transgenic A. 7120 are similar to those of the wild type of A. 7120, and the transgenic and wild type A. 7120 are able to grow normally under 10700 μE·m^-2·s^-1 with a range of different cell densities. But addition of glucose (4 g/L) into BG11 culture medium increases the growth rates of the transgenic A. 7120 in contrast to the wild type. The contents of TNF-α in the different culture ages of the transgenic A. 7120 determined in this investigation suggested that the accumulations of TNF-α in the transgenic A. 7120 cultures reached the maxima at about the eighth day. This provides a helpful message for production of TNF-α.